Thermostat switch



Jan. '10, 1933. J. R. BEERS 1,894,150

THERMOSTAT SWITCH Filed July 25, 1932 A 3 WM Patelnte d 10, 1933 JOHN B. IBEERS, OF BLOOMFIELD, JERSEY THERMOSTAT SWITCH Application filed July 25, 1982. Serial No. 624,570.

This invention relates to an enclosed thermally operated switch constructed so thatthe thermally responsive element ofthe switch will operate with the least possible delay,

u on change in temperature of the atmosphere immediately surrounding the device. The devices are used principally in rooms of buildings to close alarm or signalling circuits when the temperature of the air is increased owing to a fire. The purpose of enclosing the switch elements is to protect them from dust, moisture and chemical action, as

well as to prevent tampering with them. En-

closing the switch elements necessarily produces atime lag inthe operation of the switch and the purpose of this invention is to so construct the switch that this lag will be negligible.

In carrying out the invention, I mount the 2 switch elements in a suitable base, preferably of ceramic material, and enclose them in a casing of thin glass through which the heat from the surrounding atmosphere may be readily conducted, and I arrange the thermally responsive element of the switch so that it will be close to the glass throughout the greater part of its length, in order that there may be a thin layer of air b tween the element and the glass. With this arrangement the element responds to changes in temperature of the surrounding atmosphere almost as quickly as if the casing were not present.

In order to provide a sturdy unit with a glass casing of the requisite thinness, the casing is made in the form of a short tube or cylinder having one end closed and the other end fitted against a cylindrical boss on the base, and a thin ferrule, preferably of ceramic material, is fitted around the boss and the lower end of the casing and cemented to the boss and the casing. The thermally responsive element is U-shaped and the closed end of the casing is curved to conform to the curvature of said element.

The device has various uses and may, by suitable arrangement of the contacts, be used to close or open a circuit upon rise or fall of the surrounding atmosphere.

In the accompanying drawing,

Fig. 1 is a central vertical section through an enclosed switch adapted to close a circuit upon increase in atmospheric temperature;

Fig. 2 is a perspective view of the same, with the casing removed;

Fig. 3. is a similar view of the casing;

Fig. 4 is a similar view of the ferrule, and,

Fig. 5 is a view similar to Fig. 1 showing a switch adapted to close a circuit upon increase or decrease of atmospheric temperature.

In Figs. 1 to 4, inclusive, of the drawing,

a represents the base or support for the switch, comprising a body portion 1, flat on one side and having a cylindrical boss 2 on its opposite side. The base is preferably made of molded ceramic material, and it is formed with openings 3 and 4 which extend through the body portion and boss, these openings being in the form of slits adapted to receive end portions of flat strips of metal b and 0 which constitute switch members. Thebody portion of the base is also formed with diametrically opposite threaded openings 5 and 6 which intersect the slits 3 and 4, respectively, and screws 7 and 8 arranged in the threaded openings are adapted to engage the strips and hold them against longitudinal movement in the slits. These screws also serve as binding-posts to which the terminals of the electric circuit which is to be controlled may be attached.

The switch member 6 is shown as a straight strip of metal which projects only a short distance above the boss and is provided with 35 a suitable contact surface at its upper end. The member 0 is a relatively long bi-metallic strip having a straight lower portion which extends through the slit 4. Above the boss this strip incllnes away from the strip 6, as shown at 9, and the remainder of the strip is U-shaped, having the parallel sides 10 and 11 connected by a curved portion 12 which extends diametrically over the boss 2. The side 11 has a suitablecontact at its lower end which is normally out of engagement with the contact on the member I) and adapted to engage the latter contact when the member 0 is afi'ected by an increase in temperature.

A casing d, of; thin glass, encloses the switch casing is secured to the base by a thin ferrule 0, preferably of ceramic material, which fits closely around the boss 2' and the lower end ortion of the casing and is cemented to the oss and the casing. As thus constructed, the bi-metallic element 0 lies close to the thin lass casing throulghout the greater part of 516 le ngth of the e ement. In operation the contact members of the device shown in Figs. 1 and 3 remain se arated at ordinary room temperature; ut

should the tem rature be increased as by the breaking out o a fire, the heat will be transmitted quickly through the thin lass casing and throu h the short air space casing an the bi-metallic strip, and the latter will operate to close an electric circuit (not shown) in which the switch elements are-included.

In Fig. 5 .the structure is the same as in Figs. 1 and 2, except that the switch member b is provided wit two aced contacts 14 and 15 and the element 0 as a double contact 16 arranged between the contacts 14 and 15, and adapted to engage the contact 14 when the tem rature of the surroundin atmosphere rises above a predetermin normal and to enggge contact 15 when the temperature falls ow the normal.

What I claim is: n

1. In a thermostat switch, a base of insulating material, a tubular casing of thin glass closed at one end and havin an open end secured to the base, two switc members. se-

cured to the base and extending into said casing, one of said members being relatively short and the other member being relatively long, the latter member com r sing a U- shaped bi-metallic strip exten ding close to the casing outward from the base and thence inward toward the base, its free end adapted to engage said shorter member.

n a thermostat switch, a base of insulating material havin an annular boss, a tubutween thematerial having spaced slits extendin through its central portion and thread openings extending from its op osite sides to said slits, a tubular casing 0 thin glass closed at one end and having an open end secured to the base, two switch members comprising flat metal strips, each fitting within and projectin from one of said slits into said casing, one o said members being relatively short and theother member being relativel long, the latter member comprising a J shaped bi-metallic strip extending close to the casing outward from the base and thence inward toward the base, its free end adapted to engage said shorter member, and binding screws threaded in said threaded openin s engaging the switch members.

11 testimony whereof I afiix my si nature.

JOHN R. B ERS.

lar casing of thin g ass closed at one end and having an open end fitting a ainst said boss, a ferrule of insulating material surrounding the boss and adjacent end of the casing and cemented to the boss and casing, two switch members secured to the base and extending into said casing, one of said members being relatively short and the other member being relatively long, the latter member comprising a U-shaped bi-metallic strip extendin close to the casing outward from the base an thence inward toward the base, its free end adapted to engage said shorter member.

3. In a thermostat switch, a base of ceramic iao 

